The present invention relates to an air bag system wherein a folded air bag is inflated and expanded by means of gas. The invention also relates to a method of folding such an air bag and an apparatus for folding the same.
An example of conventional air bag systems is an air bag system incorporated in the steering wheel of a vehicle. This air bag system essentially comprises a flat, pouch-shaped air bag, a cover that covers said air bag, and an inflator adapted to eject gas. Under normal circumstances, the air bag is folded compactly and stored in the cover. The air bag system is adapted to cause gas to be ejected from the inflator in order to inflate the air bag when a shock resulting from a collision of the vehicle is detected, so that the pressure of the expansion of the air bag tears the cover and projects the air bag towards the front of the driver, where the air bag continues to be unfolded and inflated at the same time to reduce the shock received by the driver.
An example of air bag systems of this type is disclosed in Japanese Patent Laid-open No. 137591/1995, which calls for folding an air bag into a wave-like pattern along a plurality of annular creases that coaxially surround the generally cylindrical inflator, and then compressing the air bag by pushing it toward the inflator. Thus, the air bag is folded into a given shape that can be stored in the steering wheel. An air bag system having this configuration is adapted to enable the air bag to tear the cover rapidly at a low pressure and expand smoothly.
However, the above structure offered in Japanese Patent Publication No. 137591/1995 presents problems in that the configuration of a folding apparatus used for folding an air bag tends to be complicated; it is difficult to reduce production costs of the system; and that it is not always easy to fold an air bag into a compact shape, because irregular wrinkles tend to be formed in radial and other directions when the air bag folded into a wave-like pattern is pushed and compressed.
In order to solve the above problems, the present invention relates to an air bag system which is capable of folding an air bag easily into a compact shape, as well as a method and an apparatus for folding an air bag which are capable of folding an air bag easily into a compact shape, simplifying the structure of a system, speeding up of the folding process, reducing production costs and enabling the air bag to be smoothly inflated.
An air bag system according to the present invention includes an inflator adapted to eject gas and a pouch-shaped air bag adapted to be unfolded and inflated toward an occupant of the seat equipped with the air bag system by the gas injected from said inflator, wherein said air bag includes an occupant's side portion positioned in front of the inflator, three or more side portions which are folded into a wave-like pattern, located outside the occupant's side portion and continuously connected to the same, and three or more excess portions, each of which is located between each two adjacent side portions and placed along the outer face of either or both the adjacent side portions. As the side portions at which the air bag is folded into a wave-like pattern are disposed around the outer face of the inflator according to the invention, the air bag can be smoothly unfolded and expanded toward the occupant from the occupant's side portion when gas is injected. In addition, by connecting the side portions, which are folded in a wave-like pattern, to one another through the excess portions and positioning these excess portions along the outer faces of the side portions, the device according to the invention is capable of folding the air bag compactly while arranging creases in an orderly fashion and reducing irregular wrinkles which may be formed during the folding operation. Furthermore, providing three each or more side portions and excess portions enables the air bag to be easily folded into a shape which is suitable to be housed in a space having a polygonal or circular outline. In addition, the configuration also makes it possible to inject gas smoothly and rapidly into the excess portions.
By providing each excess portion with a release line portion that extends continuously from the occupant's side portion to the end of the excess portion, the invention is capable of separating the folds that constitute each side portion from those which constitute the adjacent side portions and smoothly feeding the gas along these release line portions to the portion surrounding the outer perimeter of the inflator, so that the air bag may be smoothly inflated outward.
As the excess portions can be easily formed by winding them in a uniform direction around the outer faces of the respective side portions, the invention simplifies a folding operation.
According to another feature of the invention, an air bag system includes an inflator adapted to eject gas and a pouch-shaped air bag adapted to be unfolded and inflated by the gas injected from said inflator, wherein said air bag includes a bottom portion in which a gas inlet opening is formed, and three or more side portions which are located outside the bottom portion, integrally connected to the same and folded nearly perpendicularly to the bottom portion into a wave-like pattern, the peripheral end of each side portion placed along the outer face of the side portion. With the configuration as above, the air bag can be folded compactly into a given shape in a substantially orderly fashion. Furthermore, as three or more side portions are provided, the air bag can be easily folded into a shape which is suitable to be housed in a space having a polygonal or circular outline, and it is also possible to inject gas smoothly and rapidly into the entire air bag.
By forming the bottom portion into a generally rectangular shape, the air bag can be easily folded along the edges of the bottom portion in a substantially orderly fashion into a compact shape.
By providing a release line portion between each two adjacent side portions in such a manner that each release line portion extends continuously from the bottom portion to the outer end of the side portion, the invention is capable of separating the folds that constitute each side portion from those which constitute the adjacent side portions and smoothly feeding the gas along these release line portions to the portion surrounding the outer cylindrical face of the inflator, so that the air bag may be smoothly inflated outward.
A method of folding an air bag for an air bag system according to the invention is a method of folding an air bag adapted to be unfolded and inflated by gas flown thereinto, said method calling for folding said air bag in such a manner as to form three or more side portions, and placing each excess portion formed between each two adjacent side portions along the outer face of each side portion. By folding said air bag to form a plurality of side portions and placing each excess portion formed between each two adjacent side portions along the outer face of each side portion, the method according to the invention is capable of easily folding the air bag neatly into a shape which comprises side portions and excess portions. Furthermore, by forming three or more side portions, the air bag can be easily folded into a shape which is suitable to be housed in a space having a polygonal or circular outline, and it is also possible to inject gas smoothly and rapidly into the entire air bag.
By providing a release line portion between each two adjacent side portions in such a manner that each release line portion extends continuously from the portion into which the gas is injected to the outer end of the side portion, the invention is capable of easily folding an air bag which is adapted to be smoothly unfolded and inflated outward.
According to yet another feature of the invention, the air bag folding method calls for spreading out an air bag flatly, folding the air bag by pushing the same at a plurality of locations, from the peripheral edge towards the center while limiting the height of the folds of the air bag, and placing the portions that protrude outward along the peripheral face of the folded portion. According to the method described above, as the height of the air bag is limited, it is possible to fold the air bag into a given shape simply by pushing the spread out air bag toward the center and placing the portions protruding outward along the peripheral face of the folded portion. Therefore, the invention is capable of simplifying the process of folding an air bag, thereby reducing the time required for the process, simplifying the structure of a folding apparatus used for this process, and reducing costs for the folding operation. Furthermore, as the method calls for folding an air bag around the central portion, it permits the air bag to be smoothly and rapidly unfolded and inflated from the central portion toward the occupant, when gas flows to the central portion.
An air bag folding apparatus according to the invention includes a release line forming means to form release line portions in an air bag, each release line portion continuously extending from the portion from which gas flows into the air bag to the edge of the air bag; and a folding means adapted to fold said air bag into a wave-like pattern in the state where the release line portions are held by the release line forming means so as to form side portions folded into a wave-like pattern and excess portions extending along the release line portions. According to this configuration, release line portions continuously extending from the portion from which gas flows into the air bag to the edge of the air bag are formed by using a release line forming means, and an air bag is folded into a wave-like pattern by using a folding means in the state where the release line portions are held so that side portions folded into a wave-like pattern and excess portions respectively extending along the release line portions are formed. Therefore, by placing the excess portions along the outer faces of the side portions, an air bag which has release line portions and can be smoothly unfolded and inflated outward can be easily folded.
A compressing means for compressing the side portions that are folded into a wave-like pattern may be provided so that an air bag can be folded compactly by compressing the side portions with the compressing means.
By providing a winding means for placing the excess portions around the peripheral surface of the side portions, a folding operation of an air bag can be made more convenient.
According to yet another feature of the invention, an air bag folding apparatus includes a loading portion to permit a flatly spread air bag to be placed thereon, a pushing means for pushing the peripheral edge of the air bag toward the center, and a height restricting means for restricting the distance between the air bag and said loading means. With the configuration as above, by pushing a spread out air bag inward with a pushing means, the air bag can be folded into a wave-like pattern around the central portion while the height of the air bag is limited by the height restricting means, the portions which remain unfolded and protrude outward are wound or otherwise placed around the outer face of the folded portion so that the air bag is formed into a given shape. Thus, the invention is capable of simplifying the process of folding an air bag, thereby reducing the time required for the process, simplifying the structure of a folding apparatus used for this process, and reducing costs for the folding operation. Furthermore, as the apparatus is adapted to fold an air bag around the central portion, it permits the air bag to be smoothly and rapidly unfolded and inflated from the central portion toward the occupant, when gas flows to the central portion.
According to yet another feature of the invention, an air bag folding apparatus includes a plurality of pushing means and a radial position restricting means adapted to form lug portions by limiting the movement of the portions of the air bag which are located between each respective adjacent pushing means. With the configuration as above, by forming lug portions by using the radial position restricting means when the air bag is pushed toward its center by the pushing means, each one of said lug portions located between each two pushing means and radially protruding outward from the central portion, the apparatus is capable of neatly folding the portion of the air bag pushed by the pushing means. The apparatus is also capable of folding the air bag easily into a given shape by winding or otherwise placing the lug portions around the peripheral surface of the folded portion.
According to yet another feature of the invention, an air bag folding apparatus includes a winding means for winding the portions which protrude outward around the peripheral surface of the folded portion. With the configuration as above, by winding the portion which protrude out of the folded portion around the peripheral surface of the folded portion, the apparatus is capable of folding the air bag easily into a given shape.
According to yet another feature of the invention, an air bag folding apparatus includes an insertion means adapted to insert a folded air bag into a cover for storing said air bag therein. With the configuration as above, as there is no need of a special structure for maintaining the folded shape, the above configuration enables the folding operation to be completed quickly and simplifies the production of an air bag system using an air bag prepared as above.